Racial segregation associated with new HIV infections among black heterosexuals living in the US

Krishen Samuel

Published: 24 September 2018

A greater
degree of racial segregation in urban areas of the United States is associated
with more new HIV infections among black heterosexual men and women, according
to a study by Umedjon Ibragimov and colleagues, published in the Journal of Urban Health.

Results
revealed that segregation was positively associated with HIV infection. The
authors suggest that black/white socioeconomic inequalities in education,
employment and poverty are mediators for this relationship. This study
highlights the need to address racial segregation and structural racism as
broader drivers of the HIV epidemic.

In 2016,
according to the Centers for Disease Control and Prevention (CDC), HIV
incidence in the US was 43.6 per 100,000 for black adults and adolescents
as opposed to 5.2 per 100,000 for the white population. Literature on
health disparities often cites segregation as a cause of the higher HIV burden
in the black population and traces several pathways to explain this
relationship. However, there are few empirical studies that directly
investigate this relationship.

It is
thought that segregation results in black and white households being separated
into unequal neighbourhoods, with black families being disproportionately likely
to live in neighbourhoods with multiple hazards (e.g. crime, exposure to illegal
drugs and possible incarceration) and fewer resources (e.g. high-quality schools
and housing).

Consequently,
segregation often results in higher violent crime – with the US criminal justice system
disproportionately incarcerating black men. This in turn leads to skewed sex
ratios in black neighbourhoods. In these neighbourhoods, black heterosexual women
have to choose from a smaller pool of available sexual partners, resulting in
higher chances of establishing sexual relationships with men who are at a
higher risk of having HIV. Socioeconomic inequality caused by segregation may
also contribute to higher HIV risk via a combination of injecting drug use and
transactional sex. Additionally, segregation may interfere with black residents
accessing the HIV continuum of care as a result of limited geographic access to
healthcare locally and prohibitive transportation costs to care that is further
away.

This study looks
at HIV incidence (new cases) in the heterosexual black population over eight
years, and includes a multivariable analysis in order to isolate confounding
variables and investigate possible mechanisms that link racial segregation to
HIV infection. Racial segregation was measured using an isolation index for
black residents in urban areas, while the investigated outcome was the
incidence of HIV infections per 10,000 black adult heterosexuals.

The
researchers also included a time lag of one year in their statistical analysis
to account for the time needed between the exposure (racial segregation) and
the outcome (HIV infection). While this study is strengthened by its
longitudinal design, which is better able to assess causality, the authors
recognise that one of the limitations is that it used a relatively short time
period for analysis – they only considered the period 2008-2015, starting their
analysis in 2007 to allow for the one year time lag.

The statistical
analysis clearly indicates that baseline residential segregation and the rate
of new HIV diagnoses are independently and positively associated. Thus, a 19% decrease
in baseline isolation was associated with a 16.2% reduction in new HIV
infections from 2008-2015.

The median
black isolation index was 36.6% in 2007, indicating that, in half the
geographical areas, black residents lived in a census area where more than a
third of the residents were also black. This index remained relatively stable
over time, with a 34.3% median in 2015. However, HIV diagnoses for black
heterosexuals decreased by 37.5% over this time, indicating that change in isolation over time
demonstrated weak positive association with the outcome. One possible
explanation for this might be that changes in segregation during the relatively
short study period were too small in magnitude to account for changes in the
outcome.

In 2007,
the median male to female sex ratio for black adults was 0.88 (88 men for every
100 women), indicating a relative deficit of black men in most areas. This
remained relatively stable over the study period. However, the authors did not
find any statistical evidence to suggest that skewed sex ratios in black
neighbourhoods (as a result of possible incarceration of black men) was a
mediating factor. However, they suggest that higher incarceration may not affect
HIV rates via imbalanced sex ratios, but instead through destabilising social
and sexual networks.

The authors
say that the sizable positive association between racial segregation and new
HIV infections indicates that it is a fundamental
determinant of HIV for black heterosexual populations. However, to
determine if this relationship is causal in nature (i.e. that segregation
actually causes HIV infections), it is important to identify causal mechanisms
that clearly link the two. Their statistical analysis
suggested that the relationship between racial segregation and HIV diagnoses
was mediated by factors such as rates of black educational attainment, racial
inequalities in educational attainment and racial inequalities in poverty. For
instance, there was a change of 51.4% noted in the association between
segregation and HIV infection when the percentage of black adults with no high
school diploma was added to the model. This is consistent with prior research
showing higher HIV rates for black residents in areas with lower graduation
rates.

Interestingly,
based on the authors’ interpretation of the data, they suggest that while
white/black inequality in terms of poverty may mediate the relationship between
racial segregation and HIV infection, absolute
poverty for black adults does not appear to play a mediating role. This
highlights the important role specifically played by inequalities arising from
racial disparities when it comes to HIV infection.

As
suggested by the social science and public health literature, this study’s
findings are consistent with the notion that segregation has harmful effects on
health, particularly in terms of placing individuals at risk for HIV infection,
and thus could be viewed as a fundamental cause of HIV infection in the US.
This strengthens the argument for policy interventions that directly target
social ills such as segregation and socioeconomic inequality as means of
curbing new HIV infections.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

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checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member
of your healthcare team for advice tailored to your situation.